Process for the production of shaped cellulose articles

Abstract

A method of manufacturing a cellulose-based shaped article. The method comprises subjecting a solution of lignocellulosic material, dissolved in a distillable ionic liquid, to a spinning method, wherein the ionic liquid is a diazabicyclononene (DBN)-based ionic liquid. DBN-based ionic liquids have good dissolution power, high thermal and chemical stability, lack runaway reactions and exhibit low energy consumption, due to low spinning temperatures. The shaped cellulose articles can be used as textile fibers, high-end non-woven fibers, technical fibers, films for packaging, and barriers films in batteries, as membranes and as carbon-fiber precursors.

The invention claimed is: 
     
       1. A method of manufacturing of a cellulose-based shaped article by subjecting a solution comprising a lignocellulosic material dissolved in a distillable ionic liquid to a spinning method, wherein the ionic liquid is a diazabicyclononene (DBN) based ionic liquid. 
     
     
       2. The method according to  claim 1 , wherein the DBN-based ionic liquid comprises a DBN-based cation and an anion that imparts a high basicity, in terms of the Kamlet-Taft beta (β) parameter, said DBN-based cation having a residue R, which is selected from linear and branched alkyl, typically C 1 -C 6  alkyl, alkoxy, alkoxyalkyl and aryl groups, and hydrogen. 
     
     
       3. The method according to  claim 1 , wherein the DBN-based ionic liquid comprises a 1,5-diazabicyclo[4.3.0]non-5-enium cation of the formula (I) 
       
         
           
           
               
               
           
         
         R 1  is selected from the group of hydrogen, linear and branched C 1 -C 6  alkyl, C 1 -C 6  alkoxy, C 1 -C 10  alkoxyalkyl and C 6-18  aryl groups, 
         an anion selected from halides; pseudohalides; a carboxylate; an alkyl sulphite, an alkyl sulphate, a dialkyl phosphite, a dialkyl phosphate, a dialkyl phosphonites, and a dialkyl phosphonate. 
       
     
     
       4. The method according to  claim 1 , wherein the DBN-based ionic liquid has a 1,5-diazabicyclo[4.3.0]non-5-enium cation of Formula (I) in  claim 3 , where R 1  is H, and a carboxylate anion. 
     
     
       5. The method according to  claim 1 , wherein the DBN-based ionic liquid is [DBNH][CO 2 Et] or[DBNH][OAc]. 
     
     
       6. The method according to  claim 1 , wherein the lignocellulosic material is a chemical, mechanical or chemimechanical pulp produced from wood or a non-wood source, or where the lignocellulosic material is a waste material. 
     
     
       7. The method according to  claim 1 , wherein the solution additionally comprises a lignin. 
     
     
       8. The method according to  claim 1 , wherein the lignin is derived from a lignin-containing pulp. 
     
     
       9. The method according to  claim 1 , wherein a solution comprising a lignocellulosic material dissolved in a distillable DBN-based ionic liquid is
 extruded through a spinning nozzle, 
 shaped as filament or film by stretching the film or filament while still in solution to orient the molecules, and 
 after passing through the air-gap, the fibres or film are drawn through a water-containing spin bath, where the cellulose is regenerated. 
 
     
     
       10. The method according to  claim 1 , where any type of unbleached and bleached chemical pulp is used as raw material. 
     
     
       11. The method according to  claim 1 , wherein spinning is carried out by air-gap spinning, wet spinning, or dry-jet wet spinning. 
     
     
       12. The method according to  claim 1 , where the spinning solution has a zero shear viscosity between 5,000 and 70,000 Pas at spinning conditions. 
     
     
       13. The method according to  claim 1 , where the solvent is purified by vacuum distillation. 
     
     
       14. The method according to  claim 1 , wherein the cellulose fibre produced has a dry tenacity of >35 cN/tex and a wet-to-dry tenacity of >0.80. 
     
     
       15. The method according to  claim 1 , wherein the polysaccharides present in the lignocellulosic pulp undergo negligible degradation, if any, during the process. 
     
     
       16. The method according to  claim 1 , wherein the process causes negligible water pollution due to degradation products. 
     
     
       17. The method according to  claim 1 , wherein the fibres produced are suitable for use in woven or non-woven textiles, for technical purposes, or for use as carbon-fibre precursors. 
     
     
       18. The method according to  claim 1 , wherein the shaped article is a film or a fibre.